**Stream calculus as a common foundation for linear and
non-linear systems, **

*Jan Rutten (CWI and VU, Amsterdam)*

We shall give a final coalgebra semantics for discrete-time causal linear
systems in terms of a final Mealy-type coalgebra (consisting of so-called causal
stream functions).

We'll compare this approach to the classic one (due to Kalman in the sixties)
and show that the coalgebraic perspective has certain advantages, which are to
do with generality (the class of linear systems we treat is mildly more general
than in the classical case), simplicity (due to a systematic use of streams and
stream derivatives), and unification (linear and non-linear systems are treated
the same).